Which algorithm is used to calculate the 12 digit Aadhaar number?

The Verhoeff algorithm is used to calculate the 12th digit of the Aadhaar number, which serves as a checksum digit. This algorithm is essential for validating the entire 12-digit unique identifier. It helps in detecting common errors, such as single-digit mistakes or transposition errors, that may occur during data entry or transmission, ensuring the integrity of the Aadhaar number format.